Vehicular power unit mount structures having displacement stoppers provided at different positions are known as disclosed, for example, in Japanese Patent Laid-open Publication No. HEI 5-126187.
The disclosed power unit mount structure, as illustrated here in FIG. 6, comprises a lower case member 102 having a lower attachment bolt 101, a flanged cylindrical member 104 having an upper attachment bolt 103, and a rubber member 106 chemically bonded to the lower case member 102 and the flange member 104 to elastically connecting them together. The flanged cylindrical member 104 is embedded in the rubber member 106 such that the rubber member 106 includes an upper abutment portion 108 formed on a lower surface of an upper annular flange 107 of the cylindrical member 104, a lower abutment portion 112 formed on an upper surface of a lower annular flange 111 of the cylindrical member 104, and a circumferential abutment portion 114 formed on a cylindrical surface of a body 113 of the cylindrical member 104 disposed between the upper and lower abutment portions 108 and 112. An upper case member 118 is clinched at a lower end to the lower case member 102 and narrowed at an upper end so as to form a ring-like stopper portion 117 received in an annular space defined between the upper and lower abutment portions 108, 112 and the circumferential abutment portion 114 of the rubber member 106.
With this arrangement, when the flanged cylindrical member 104 is displaced in a vertical direction relative to the case members 102, 118, the upper abutment member 108 or the lower abutment member 112 may abut on the stopper portion 117 to thereby stop or restrict the vertical displacement of the flanged cylindrical member 104. Alternatively, when the flanged cylindrical member 104 is displaced in a horizontal direction relative to the case members 102, 118, the circumferential abutment portion 114 may abut on the stopper portion 117 so that further horizontal movement of the cylindrical member 104 does not occur.
The known power unit mount structure shown in FIG. 6 is disadvantageous in that due to a complicated configuration of the flanged cylindrical member 104, chemical bonding of the rubber member 106 relative to the flanged cylindrical member 104 is uneasy to achieve. Performance characteristics of abutment portions (displacement stoppers) 108, 112 and 114 depend largely on the amount of displacement of the flanged cylindrical member 104 and the hardness of the rubber member 106. To change the performance characteristics of the displacement stoppers 108, 112, 114, the shape and the material of the rubber member 106 need to be changed. However, such change is uneasy to achieve because the displacement stoppers 108, 112, 114 are chemically bonded as parts of the rubber member 106 to the flanged cylindrical member 104.
It is accordingly an object of the present invention to provide a vehicular power unit mount structure having displacement stoppers which are easy to manufacture and also easy to change performance characteristics of the displacement stoppers.